.\" Copyright (c) 1983, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)lpd.8	6.6 (Berkeley) 3/16/91
.\"
.Dd March 16, 1991
.Dt LPD 8
.Os BSD 4.2
.Sh NAME
.Nm lpd
.Nd line printer spooler daemon
.Sh SYNOPSIS
.Nm lpd
.Op Fl l
.Op Ar port#
.Sh DESCRIPTION
.Nm Lpd
is the line printer daemon (spool area handler) and is normally invoked
at boot time from the
.Xr rc 8
file.  It makes a single pass through the
.Xr printcap 5
file to find out about the existing printers and
prints any files left after a crash. It then uses the system calls
.Xr listen 2
and
.Xr accept 2
to receive requests to print files in the queue,
transfer files to the spooling area, display the queue,
or remove jobs from the queue.  In each case, it forks a child to handle
the request so the parent can continue to listen for more requests.
.Pp
Available options:
.Bl -tag -width Ds
.It Fl l
The
.Fl l
flag causes
.Nm lpd
to log valid requests received from the network. This can be useful
for debugging purposes.
.It Ar "port#"
The Internet port number used to rendezvous
with other processes is normally obtained with
.Xr getservbyname 3
but can be changed with the
.Ar port#
argument.
.El
.Pp
Access control is provided by two means. First, all requests must come from
one of the machines listed in the file
.Pa /etc/hosts.equiv
or
.Pa /etc/hosts.lpd .
Second, if the
.Li rs
capability is specified in the
.Xr printcap
entry for the printer being accessed,
.Em lpr
requests will only be honored for those users with accounts on the
machine with the printer.
.Pp
The file
.Em minfree
in each spool directory contains the number of disk blocks to leave free
so that the line printer queue won't completely fill the disk.
The
.Em minfree
file can be edited with your favorite text editor.
.Pp
The daemon begins processing files
after it has successfully set the lock for exclusive
access (descibed a bit later),
and scans the spool directory
for files beginning with 
.Em cf .
Lines in each
.Em cf
file specify files to be printed or non-printing actions to be
performed.  Each such line begins with a key character
to specify what to do with the remainder of the line.
.Bl -tag -width Ds
.It J
Job Name.  String to be used for the job name on the burst page.
.It C
Classification.  String to be used for the classification line
on the burst page.
.It L
Literal.  The line contains identification info from
the password file and causes the banner page to be printed.
.It T
Title.  String to be used as the title for
.Xr pr 1 .
.It H
Host Name.  Name of the machine where
.Xr lpr
was invoked.
.It P
Person.  Login name of the person who invoked
.Xr lpr .
This is used to verify ownership by
.Xr lprm .
.It M
Send mail to the specified user when the current print job completes.
.It f
Formatted File.  Name of a file to print which is already formatted.
.It l
Like ``f'' but passes control characters and does not make page breaks.
.It p
Name of a file to print using
.Xr pr 1
as a filter.
.It t
Troff File.  The file contains
.Xr troff 1
output (cat phototypesetter commands).
.It n
Ditroff File.  The file contains device independent troff
output.
.It r
DVI File.  The file contains
.Tn Tex l
output
DVI format from Standford).
.It g
Graph File.  The file contains data produced by
.Xr plot 3 .
.It c
Cifplot File. The file contains data produced by
.Em cifplot .
.It v
The file contains a raster image.
.It r
The file contains text data with
FORTRAN carriage control characters.
.It \&1
Troff Font R. Name of the font file to use instead of the default.
.It \&2
Troff Font I. Name of the font file to use instead of the default.
.It \&3
Troff Font B. Name of the font file to use instead of the default.
.It \&4
Troff Font S. Name of the font file to use instead of the default.
.It W
Width. Changes the page width (in characters) used by
.Xr pr 1
and the text filters.
.It I
Indent.  The number of characters to indent the output by (in ascii).
.It U
Unlink.  Name of file to remove upon completion of printing.
.It N
File name.  The name of the file which is being printed, or a blank
for the standard input (when 
.Xr lpr
is invoked in a pipeline).
.El
.Pp
If a file can not be opened, a message will be logged via
.Xr syslog 3
using the
.Em LOG_LPR
facility.
.Nm Lpd
will try up to 20 times
to reopen a file it expects to be there, after which it will
skip the file to be printed.
.Pp
.Nm Lpd
uses
.Xr flock 2
to provide exclusive access to the lock file and to prevent multiple
deamons from becoming active simultaneously.  If the daemon should be killed
or die unexpectedly, the lock file need not be removed.
The lock file is kept in a readable
.Tn ASCII
form
and contains two lines.
The first is the process id of the daemon and the second is the control
file name of the current job being printed.  The second line is updated to
reflect the current status of
.Nm lpd
for the programs
.Xr lpq 1
and
.Xr lprm 1 .
.Sh FILES
.Bl -tag -width "/var/spool/*/minfree" -compact
.It Pa /etc/printcap
printer description file
.It Pa /var/spool/*
spool directories
.It Pa /var/spool/*/minfree
minimum free space to leave
.It Pa /dev/lp*
line printer devices
.It Pa /dev/printer
socket for local requests
.It Pa /etc/hosts.equiv
lists machine names allowed printer access
.It Pa /etc/hosts.lpd
lists machine names allowed printer access,
but not under same administrative control.
.El
.Sh SEE ALSO
.Xr lpc 8 ,
.Xr pac 1 ,
.Xr lpr 1 ,
.Xr lpq 1 ,
.Xr lprm 1 ,
.Xr syslog 3 ,
.Xr printcap 5
.Rs
.%T "4.2 BSD Line Printer Spooler Manual"
.Re
.Sh HISTORY
An
.Nm
daemon appeared in Version 6 AT&T UNIX.
